20821335616 has 63 divisors (see below), whose sum is σ = 43932142387. Its totient is φ = 9789040640.

The previous prime is 20821335569. The next prime is 20821335671. The reversal of 20821335616 is 61653312802.

The square root of 20821335616 is 144296.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 4050049600 + 16771286016 = 63640^2 + 129504^2 .

It is a super-2 number, since 2×20821335616² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 19623726 + ... + 19624786.

Almost surely, 2^20821335616 is an apocalyptic number.

20821335616 is the 144296-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20821335616

20821335616 is an abundant number, since it is smaller than the sum of its proper divisors (23110806771).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20821335616 is an frugal number, since it uses more digits than its factorization.

20821335616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2168 (or 1080 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 20821335616 in words is "twenty billion, eight hundred twenty-one million, three hundred thirty-five thousand, six hundred sixteen".